Retinal implant with improved implantation and working properties

ABSTRACT

The invention relates to a retinal implant having at least one functional unit  4  positioned internally inside an eye and at least one functional unit ( 2 ) positioned externally outside the eve and at least one functional unit  8  position outside the eye, which are separably connected to one another via a signal path ( 5, 6, 7, 15, 16, 17; 10, 11, 12, 15, 16, 17 ) in a manner designed for signal or data transmission. The patient&#39;s residual vision which may still remain is preserved because the signal path extends through the sclera ( 9 ) of the eye and does not incorporate the anterior eye section.

[0001] The present invention relates to a retinal implant having thefeatures of the precharacterising clause of claim 1.

[0002] An implant according to the generic type is known from U.S. Pat.No. 5,935,155. This document proposes that a functional unit (IGF)positioned inside the vitreous chamber be connected to an externallypositioned functional unit (EPF) via wireless coupling of two coils. Thecoil of the internal functional unit is in this case arranged in thelens behind the iris.

[0003] In addition to the surgical intervention on the vitreous body forimplanting the functional unit (IGF) positioned inside the vitreouschamber, a second surgical intervention is necessary in the anterior eyesection for implanting the coil or a second functional unit (AGF)positioned outside the vitreous chamber (especially in the lenticularcapsule in place of the intraocular lens (IOL), which needs to beremoved before-hand).

[0004] The second functional unit (AGF), which is implanted in thelenticular capsule and is provided, in particular, in the case ofvarious retinal implants, is mechanically connected to the IGF via amicrocable and, in currently available versions, cannot be temporarilyseparated and re-connected. Technical solutions for this are, however,available. This mechanical connection makes the surgical interventionssignificantly more difficult since, when implanting the AGF in thelenticular capsule envelope, it is also necessary to make an opening inthe lenticular capsule wall and to transfer the IGF, with the microcableconnection, through this opening into the vitreous chamber. This entailsadditional risk factors such as: mechanical destabilisation of thelenticular capsule envelope by the additional opening; mechanical stresson the implant components, including the microcable; lengthening of theimplantation time; increase in the risk of future pathological tissuechanges, which may make the implant function or further surgicalinterventions (such as e.g. re-explantation) difficult or impossible.

[0005] Positioning the AGF in the anterior eye segment significantlyrestricts optical access to the retina and to the IGF. This can have adetrimental effect both on the function of the implant system and onsight, as well as on the medical inspectability of the vitreous chamber.

[0006] Externally positioned functional units (EPF) located outside thebody are positioned immediately in front of the eye, in the normal fieldof view of the eye, in place of a spectacle lens or a contact lens, andhence impede any partial sight which may still remain (e.g. in subjectswith macular degeneration and remaining extrafoveal vision).

[0007] As the signal processing effort rises, especially in the case ofretinal implants, when the number of microcontacts increases, the massand energy demand of the microelectronic components rises significantly,so that in this context a limit for intraocularly implantable functionalunits is rapidly reached and the desired functional quality of theimplant is thereby substantially restricted.

[0008] It is therefore an object or the present invention to provide aretinal implant in which the connection between the internal functionalunit IGF and at least one external functional unit (AGF, EPF) does notinterrupt the optical path between the lens and the extrafoveal regionof the retina, and in which this connection is wireless or can bemechanically separated during implantation.

[0009] This object is achieved by a retinal implant having the featuresof claim 1. Because the signal path extends through the sclera of theeye, inside the eye socket bounded by the conjunctiva, the optical pathfrom the lens to the retina outside the foveal region remains free. Theseparability of the signal path permits separate implantability of thecomponent implanted inside the eye and the component implanted outsidethe eye in the eye socket.

[0010] Advantageous embodiments are given in the dependent claims.

[0011] Two exemplary embodiments of the present invention will bedescribed below with reference to the drawing, in which:

[0012]FIG. 1 shows an implant with a wireless inductive connectionbetween the internal functional unit and a second functional unitimplanted outside the eye;

[0013]FIG. 2 shows a similar implant to FIG. 1, with a separable plugconnection between the internal functional unit and a second functionalunit implanted outside the eye; and

[0014]FIG. 3 shows a perspective representation of the implant accordingto FIG. 1

[0015]FIG. 1 represents a retinal implant or patients having adegenerative disease of the retina 1, in which the functional unit (EPF)2 present outside the body is positioned in the head region (e.g. on theside of a spectacle frame with normal spectacle function), in such a waythat the optical beam path between viewed objects and the retina 1 isimpaired neither by functional units directly in front of the eye nor byfunctional units in the anterior eye segment, including the intraocularlens (IOL) 3, and in such a way that, in particular, patients canthereby use their residual vision which may still remain (e.g. in theextrafoveal field of view in the case of macular degeneration), inaddition to the implant function.

[0016] In a retinal implant according to the invention, the functionalunit IGF 4 positioned inside the vitreous chamber is designed as amicrocontact foil having associated microelectronics, a microcable 5 andat least one coil 6, and is fastened close to the retina in a suitableway. Via this coil 6 as part of the IGF 4 and at least one correspondingcoil 7 as part of the AGF 8 inside the eye socket, a communicationconnection is made inductively through the sclera 9. Since the signalpath through the sclera 9 of the eye extends inside the eye socketbounded by the conjunctiva 19, the optical path from the lens to theretina outside the foveal region remains free. The separability of thesignal path permits separate implantability of the component implantedinside the eye and the component implanted outside the eye in the eyesocket.

[0017]FIG. 2 illustrates another embodiment of a retinal implantaccording to the invention. In this case, the transscleral connectionbetween the IGF 4 and the AGF 8 is made galvanically via a microcable10, the microcable being mechanically separated at a plug connection 11during implantation, and the connection being made subsequently. Such amicrocable connection 10 which can be made subsequently between the IGF4, which e.g. performs only retinal stimulation, and an AGF 8 whichundertakes decoder and/or demultiplexing functions, and which isimplanted but located outside the eye, may preferably be configured insuch a way that, according to the ophthalmological state of the art, asuitable transscleral cannula 12 is permanently implanted, themicrocable 10 is fed through it, and the passage is sealed afterwards.The subsequent microcable connection 10 may furthermore be designed insuch a way that the two ends to be galvanically connected (correspondingto a male or female plug connector) carry an equal number ofcomplementarily shaped metal contacts (e.g. as pins at one cable end andas sockets at the other cable end) which, during the separateimplantation of the IGF 4 and the AGF 8, are covered with an insulatingthin plastic film for protection against the effect of fluids.

[0018] In a preferred embodiment, the microcable connection isestablished in that the pin part 11 and the socket part 11′ arepositioned flat facing one another while aligning the rows of pins andcorresponding sockets, and in that the pin part and the socket part canthereupon be pressed cleanly against one another in such a way that, onthe one hand, the insulating film is pierced and, on the other hand,securely insulated galvanic connections of the corresponding microcablelines 10 are made even under wet environment constraints

[0019] In a preferred embodiment, this microcable connection cansubsequently be re-separated by a suitable separating tool.

[0020] This separable microcable connection, consisting of the pin part11 and the socket part 11′, can preferably be produced both outside theeyeball in the eye socket (see FIG. 2) and inside the vitreous chamber(no image).

[0021] In likewise advantageous embodiments, the wireless transscleralcommunication is produced optoelectronically or by ultrasonictransmitter and receiver pairs on both sides of a circumscribed scleralzone.

[0022] In another embodiment, a cannula 12 is arranged in the wall ofthe sclera 9 according to the ophthalmological state of the art, and isshut off by a permeable film in the manner of a closed window.

[0023] In another embodiment, the AGF 8 is fastened sclerally to theouter wall of the bulb according to the ophthalmological state of theart (adhesive bonding, pinning or suturing) and has, in addition to amicrocable 5 and at least one primary coil 7 fastened sclerally facingthe respective corresponding coil 6 in the vitreous chamber, a furthermicrocable 15 for connection to the functional unit (EPF) 2 locatedoutside the body.

[0024] In a preferred embodiment, the connection between the AGF 8 inthe eye socket and the external EPF 2 is made inductively via a coilpair 16, 17 and associated transmission and reception electronics 18,this coil pair 16, 17 being separated by a skin region in the head area(e.g. on the forehead) and the microcable 15 from the AGF 8 to thesecondary coil 16 and the reception electronics 18 of this preferablytranscutaneous inductive connection being laid under the skin accordingto the surgical state of the art.

[0025] In another possible version, the connection between the AGF 8 inthe eye socket and the external EPF 2 is made via a suitable catheterstructure and/or cable structure (not shown).

[0026] In an advantageous embodiment, in order to set up a functionoutside the normal implant operation, optical and/or optoelectroniccommunication is produced between a functional unit located outside thebody and the IGF 4 in the vitreous chamber.

[0027] The external functional unit 2, which may comprise an encoder aswell as camera means, may also, in one embodiment according to theinvention, be worn by the patient in a manner other than with theconventional spectacle-type arrangement. For instance, the requisitecomponents may also be arranged in a cap or a headband, which make itpossible to avoid wearing spectacles which may be uncomfortably heavy.This furthermore permits the use of larger components, which aresuitable for processing a larger number of optical channels or pixels.

1. Retinal implant having at least one functional unit 4 positionedinternally inside an eye and at least one functional unit 2 positionedexternally outside the eye, which are connected to one another via asignal path (5, 6, 7, 15, 16, 17; 10, 11, 12, 15, 16, 17) in a mannerdesigned for signal or data transmission, characterised in that thetransscleral signal-path segment between the functional units (4, 8) canbe separated, and in that the signal path between the functional units(2, 4) does not incorporate the anterior eye section, including thecornea and intraocular lens.
 2. Implant according to claim 1,characterised in that the signal path comprises a wireless inductiveconnection (6, 7) which has a respective transmission and receptionelement inside (6) and outside (7) the eye, which are arranged facingone another, the sclera (9) lying between the transmission and receptionelements (6, 7).
 3. Implant according to claim 1, characterised in thatthe signal path comprises a galvanic connection (10, 11, 11′) whichpasses through the sclera.
 4. Implant according to claim 3,characterised in that the galvanic connection (10, 11, 11′) can beconnected after implantation, and preferably disconnected, at mutuallycomplementary contact elements (11, 11′).
 5. Implant according to one ofthe preceding claims, characterised in that the sclera (9) is penetratedby a cannula (12) which is used for feeding an electrical cable (10)through.
 6. Implant according to one of the preceding claims,characterised in that a functional unit (8) implanted outside the eye,which is designed to carry out signal processing functions, is provided.